Murray, Nishikori into US open quarters

It may have been the Labor Day holiday in the United States on Monday, but Andy Murray came ready to work.

Murray demolished Grigor Dimitrov 6-1 6-2 6-2 to storm into the quarter-finals of the US Open.

With the year’s final grand slam entering its second week, Murray posted a statement win by dispatching the 22nd-seeded Bulgarian in two hours.

It signalled he is well prepared to extend a dream summer that has included a second Wimbledon title and a second Olympic gold medal.

Dimitrov, who ended Murray’s title defence at the 2014 Wimbledon and came out on top in their last meeting earlier this season in Miami, represented a potentially tricky opponent for the second-seeded Scot.

But Murray was firing on all cylinders, rating the match that included a career-high 227kph ace to close out the first set as one of his best this season.

“It was definitely up there,” Murray said.

“I played very well today with very few unforced errors and made it very tough for Grigor.”

Next up for Murray is Japan’s Kei Nishikori, a 6-3 6-4 7-6 (7-4) winner over Ivo Karlovic.

Nishikori cut down the towering Croatian with surgical precision.

The US Open runner-up two years ago, Nishikori will go down as the winner of the last final main draw singles match at Louis Armstrong Stadium.

The arena will be replaced by a new stadium with a retractable roof for the 2018 tournament.

It was a David and Goliath clash of physical opposites, but the 211cm Karlovic’s game, apart from his prodigious serve, was overshadowed by the skills of the 178cm Nishikori.

“I made a lot of returns off first and second serves and was happy with my return game today,” Nishikori said.

Nishikori, who became the first Asian to reach a grand slam men’s final two years ago in Flushing Meadows, has had a strong season, including a run to the quarters at the Australian Open before falling to eventual winner Novak Djokovic.

Two-time major champion Stan Wawrinka blew a lead and smashed a racquet before pulling out a four-set victory to reach the quarters at Flushing Meadow for the fourth consecutive year.

After saving a match point in a five-set win in his last outing, Wawrinka was cruising against 63rd-ranked Illya Marchenko, who was playing in his first grand slam round of 16.

Serving for the match in the third set, the third-seeded Wawrinka was broken and went on to lose a tiebreaker.

After going down a break early in the fourth, Wawrinka took his frustrations out on his racquet.

He proceeded to win the next four games to regain control on the way to a 6-4 6-1 6-7 (7-5) 6-3 victory.

Wawrinka faces 2009 US Open champion Juan Martin del Potro, who beat him at Wimbledon this year.

Del Potro booked his spot in the final eight when Dominic Thiem retired in the second set of their match.

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